Current wind turbine blade certification requires performing several static tests on the blade to confirm the blade capability to withstand the expected loads, particularly static strength tests to check the blade behaviour under extreme design loads, fatigue tests to check the blade's ability to withstand the operating loads for its design life and other tests in order to characterize physical properties of the blade such as weight, centre of gravity or natural modes and frequencies.
These tests are usually carried out in a test bench in which the blade is bolted to a rigid structure and then static or dynamic loads are applied to the blade by means of different methods.
Current test systems rely on a set of strain gauges to determine the strain distribution along blades. With the increasing size of blades, the amount of necessary gauges is rapidly growing, which implies larger efforts to adequately estimate the aforementioned distribution. With two to four electrical wires per gauge, cabling volume, complexity and vulnerability to electro-magnetic interference become significant and disturbing. Additionally, the discrete nature of this kind of measurements implies loss of information in case of non-linear behaviour in the area between two strain gauges.
This invention is intended to the solution of said problems.